In commercial gravity aided liquid dispensing systems, such as for dispensing dairy products, large amounts of product are required on-site. For example, coffee shops and fast food restaurants serve a large number of people each day. For this reason, it is unsuitable to have a refrigerator for the server to access cartons and small milk bags typically used by the average consumer. Furthermore, refrigerators occupy a significant amount of space which is limited in a fast food restaurant location.
Refrigerated dairy dispensing machines have been developed to address this problem. One such machine is configured to receive a 10 L bag of dairy product in an enclosed refrigerated space and optimized in size to sit on a countertop. A preconfigured outlet of the bag is attached to a corresponding valve system to control dispensing of the dairy product by gravity.
Because the bag cannot structurally support itself, a product case or caddy constructed of a rigid material such as plastic, is used to hold the bag. FIGS. 1A, 1B and 10 shows different views of an example product case sized to receive and hold a 10 L bag of fluid. FIG. 1 a shows a front view of a product case 10 which in the present example has a handhold opening 12 and an outlet access opening 14. The floor 16 includes an opening sized and shaped to receive an outlet 18 of the liquid bag placed inside. In this particular configuration, the outlet 18 slides into the opening of the floor 16 and is latched therein to prevent it from moving. The product case 10 typically has an open top to allow for easy insertion of the liquid bag by a user.
FIG. 1B is a top view of the product case 10 shown in FIG. 1A. An outline of the liquid bag 20 is shown, and when full, would typically fill most of the floor area and press against the side walls of the product case 10. Such bags are filled to the maximum volume. FIG. 1C is a cross-section side view of the product case 10 with liquid bag 20, taken along line A-A of FIG. 1B. Dispensing fluid from the bag when it is full is reliable because there is sufficient head pressure from the liquid itself to push the liquid out through the outlet 18. However, as the liquid bag 20 drains over the course of multiple dispenses, the loose material of the bag will collapse onto the surface of the liquid.
Experiments have shown that the last 500 mL liquid in the bag 20 is problematic because the loose material of the bag 20 does not collapse repeatedly or reliably in the same direction, even though special fold lines are formed in the bag 20. As a result, the loose material of the bag can collapse onto the outlet 18 and block or impede the remaining liquid from draining, or creating folds or pockets where product can be trapped. In this situation, the user will deem the bag empty and switch it out for a full bag, resulting in non-dispensed product being thrown away.
This problem also exists in situations where a smaller liquid bag, such as a 5 L liquid bag is used in a product case configured for receiving a 10 L liquid bag. FIG. 2 shows a top view of the same 10 L product case 10, but this time having a 5 L liquid bag 22 having an outlet 24 inserted therein. In FIG. 2, the outline of the 5 L liquid bag 22 is shown assuming the bag is full. Over time as the liquid in the bag 22 is drained, the loose material of the liquid bag 22 may stretch out to the rear of the product case 10 as shown by the dashed lines 26. This is because the liquid in the bag will tend to spread out over the area of the floor of the product case 10 as constrained by the sidewalls. Not only does this affect the head pressure characteristics, the material of the liquid bag 22 also does not collapse repeatedly or reliably in the same direction even though special fold lines are formed in the bag 22. The loose material will collapse over the outlet 18 thereby preventing any remaining product from being dispensed, or the loose material will create folds or pockets where product can be trapped.
In some applications, speed of service for dispensing liquid from the bag is required. In such situations a smaller liquid bag, such as a pillow bag is positioned such that it is standing up and not lying flat on its larger surface. Unfortunately by standing the pillow bag up, it becomes inherently unstable and will likely fall over in some random direction that could also result in wasted liquid product that cannot be dispensed.
Therefore, it is desirable to provide a system that minimizes waste of liquid product in a liquid bag and provides repeatable flow characteristics.